Back ~152 years ago, when I was building 1956 F-100 "street rod" trucks, the hot tip was to find a '68-'71 Thunderbird and use the entire front clip; in other words, cutting the frame of the T-Bird off at the firewall and swapping it out w/the F-100 clip - and of course also using the 429 engine and that big ole' C-6 trannie...
MY thoughts, in no particular order:
1). Even w/aluminum heads, intake, etc., there is NO WAY that that powerplant is going to be "close to the same weight" as even an all iron 302; might wanna check your math on that again, IF it's important to you...
2). That engine is a torque MONSTER, which is great; not sure what your intended application is. Be prepared for some MONSTER fuel costs to go along with it!
3). I too keep coming back to the idea of a BB engine for my own '69 Bronco; my choice however would be a 427 BB in all aluminum configuration. I believe that the 427 would be a better overall fit in-between the shock towers of a Bronco, but hey, I'm spitballing it here...
Not meaning to rain on your parade, 'cause I ALWAYS like me some Big Block power! I would check your weight #'s a few times over, however - you may just be building yourself a "straight line Bronco" here...